400 – Bad request
What does it mean?
There’s something wrong with the URL you typed. Maybe the server you’re contacting doesn’t recognize the document you’re asking for, maybe it doesn’t exist, or maybe you’re not authorized to access it.
What can you do about it?
Check the URL. Pay special attention to uppercase and lowercase letters, colons, and slashes. Here’s a tip: one style convention many sites observe is to slap initial capital letters on directory names but not file names. If you get this message repeatedly, maybe you copied the URL and mixed up its uppercase and lowercase.
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401 – Unauthorized
What does it mean?
You’re probably accessing a site that’s protected and you’re not on the host’s preferred guest list or you typed the password incorrectly. Some sites also put a block on domain types–if you’re not from a .gov or .edu domain, for example, you may not be able to gain access.
What can you do about it?
If you’re sure you’re allowed in, try again, and this time look at the keyboard when you type. Passwords are often case-sensitive, so if you’ve got your Caps Lock on, take it off. If you’re trying to break in, we don’t want to know, but the odds are stacked against you.
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403 – Forbidden
What does it mean?
You may not be allowed to access this document, probably because it’s either blocked to your domain or it’s password-protected.
What can you do about it?
If you know the password, try again, carefully. If you don’t know the password but think you’re eligible for one, contact the site’s Webmaster and ask for it.
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404 – Not found
What can you do about it?
Try going one level up (deleting the last part of the URL to the nearest slash) to see if the site is live. If it is, check if there are links to the document you’re looking for. Failing that, delete the last slash and type .html instead, and see what that gives you.
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503 – service unavailable
What does it mean?
There are a variety of possibilities: your access provider’s server may be down, your company’s gateway (the connection between the LAN and the Internet) may be broken, or your own system isn’t working.
What can you do about it?
This is usually an easy one: wait a minute and try again. If the error persists, identify the culprit (access provider, gateway, or your system) by process of elimination.
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Bad file request
What does it mean?
Your browser supports forms complete with data-entry fields and drop-down lists, but not the form you’re trying to access. Perhaps there’s an error or unsupported feature in the form.
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Cannot add form submission result to bookmark list
What does it mean?
You’ve just entered a search request and tried to save the result as a bookmark. Though it may appear as a discrete address, the result isn’t a legitimate URL, so you can’t add it to your bookmark list.
What can you do about it?
Try saving the result page as an HTML page on your hard disk. Use the Save As command then add the saved page to your bookmark list. Depending on the CGI script behind the query, you may or may not be successful. But it’s worth a try.
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Connection refused by host
What does it mean?
You may not be allowed to access this document, probably because it’s either blocked to your domain or it’s password-protected.
What can you do about it?
If you know the password, try again, carefully. If you don’t know the password but think you’re eligible for one, contact the site’s Webmaster and ask for it.
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Failed DNS lookup
What does it mean?
The domain name system can’t translate the URL to a valid Internet address. This is either a harmless blip or the result of a mistyped URL (specifically, a mistyped host name).
What can you do about it?
Blips in DNS lookup are common, and often you can rectify this by clicking the Reload button. If that doesn’t work, check your typing of the URL carefully. If the problem persists, try again after an hour or so.
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File contains no data
What does it mean?
The site you’ve accessed is the right one, but there are no Web page documents on it. You may have stumbled upon this site just as updated versions are being uploaded.
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Helper application not found
What does it mean?
Your browser doesn’t recognize a file at the Web or Net site you’re visiting. Most browsers can be extended using helper applications (or viewers) to read files they don’t otherwise recognize. These files aren’t necessarily graphics–they can be sound files, movie clips, or ZIP or SIT archive files you’re trying to download.
What can you do about it?
The dialog box that carries this message will usually give a clue about the file type that’s missing. (You may see some gibberish about octet streams, but after that you’ll probably see some reference to graphic-TIFF, which gives it away.) Look at CompuTREK’s Help for your computing platform (Mac or PC) for viewers for the most common file types. Then follow your browser’s instructions for assigning a viewer for each file format you wish to view online.
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Host unavailable
What does it mean?
The machine that hosts this site is probably down for maintenance.
What can you do about it?
If at first you don’t succeed, hit Refresh or Reload again and again. But wait a while between refreshes.
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Host unknown
What does it mean?
The server may be down for maintenance, or you may have lost the connection (your modem disconnected, or your company’s T1 line is choking).
What can you do about it?
Hit the Reload button first. This is often a blip in the Net. Then check the URL for typos (and don’t forget case-sensitivity). Then make sure you’re connected by hitting Reload, which will re-establish connections in many cases.
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Network connection was refused by the server
What does it mean?
The server is probably too busy to handle one more user, but it’s not configured to generate its own message, so this generic message shows up instead.
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NNTP server error
What does it mean?
You’re trying to log on to a Usenet newsgroup, but you can’t get to it. The Usenet server is something that’s made available by your Internet service provider, so it may be that this newsgroup isn’t available at all.
What can you do about it?
Make sure you’ve typed the URL correctly. If that doesn’t help, try again later.
